Investigations on laser texturing of helical gears to enhance their quality by abrasive flow finishing process

Abstract

Higher wear resistance, lower noise level, enhance power transmission capability, better transmission efficiency, operating performance and longer service life are continuously growing expectations from the gears. These expectations can be met by manufacturing gears of high quality. High quality gears can be manufactured by minimizing microgeometry errors, surface roughness error and improving surface integrity (i.e. residual stresses, microhardness, microstructure etc.) of the gear flank surfaces by appropriate gear finishing process.Laser texturing provides micro-reservoirs to enhance lubricant retention or micro-traps to capture wear debris. Presence of micro-texture improves friction and wear characteristics. But it gives excess molten and re-solidified material on the laser textured surface. These need to be removed by appropriate finishing processes to achieve the intended surface geometry and quality. Abrasive flow finishing (AFF) is an advanced finishing process which can be used to improve the characteristics of gears. Present work is focused upon laser texturing of helical gears to enhance their quality during their finishing by AFF process. This is done by modifying the lay profile generated on the surface of gear flank by gear hobbing using laser surface texturing. Three different laser texturing patterns namely homothetic, circular and cross have been used and their effect on the surface roughness, microgeometry, microhardness and wear resistance of helical gear flank surfaces has been studied. Quality of AFF finished hobbed helical gears and laser textured and then AFF finished helical gear was compared in terms of deviations in their microgeometry (i.e. profile, lead, pitch and runout), surface quality (i.e. averagesurface roughness, maximum surface roughness), material removal rate, microhardness and wear rate. It was observed that all three-laser textured helical gears when finished by AFF produced higher improvement as compared to the AFF finished hobbed helical gears. Also, the effect of individual laser texturing patterns is studied, and it was observed that the texturing having the cross pattern on the gear flank surface produced highest improvement in surface roughness and microgeometry.